Influence of Compensatory Renal Growth on Susceptibility of Primary Cultures of Renal Cells to Chemically Induced Injury

Toxicological Sciences, Dec 2006

Primary cultures of rat renal proximal tubular (PT) and distal tubular (DT) cells from control and uninephrectomized (NPX) Sprague-Dawley rats were established to study whether the altered toxicological responses identified in freshly isolated cells are maintained in culture. Previous work showed that primary cultures of PT cells from hypertrophied rat kidneys maintained their differentiated properties, as evidenced by their high respiratory rate, active transport function, transport and metabolism of glutathione, and their hypertrophic phenotype. In the present study, primary cultures of PT cells from NPX rat kidneys, but to a much lesser extent DT cells, were more susceptible to cellular injury induced by either mercuric chloride, KCN, or tert-butyl hydroperoxide (tBH), than corresponding cells from normal rat kidneys. Direct comparisons of cytotoxicity and lipid peroxidation induced by tBH in freshly isolated renal cells showed that the primary cultures of cells from NPX rat kidneys retained their altered susceptibility relative to cells from control rats. These results show that primary cultures of PT cells from NPX rats are more sensitive to cellular injury induced by three mechanistically distinct toxicants, demonstrating their usefulness in the study of the molecular and biochemical basis for the altered phenotype of compensatory renal growth. This is the first report validating the use of a mammalian renal cell culture model to study the toxicological effects of compensatory renal cellular hypertrophy.

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Influence of Compensatory Renal Growth on Susceptibility of Primary Cultures of Renal Cells to Chemically Induced Injury

Advance Access publication September Influence of Compensatory Renal Growth on Susceptibility of Primary Cultures of Renal Cells to Chemically Induced Injury Lawrence H. Lash 1 2 David A. Putt 1 2 Rudolfs K. Zalups 0 1 0 Division of Basic Medical Sciences, Mercer University School of Medicine , Macon, Georgia 31207 , USA 1 The Author 2006. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved 2 Department of Pharmacology, Wayne State University School of Medicine , Detroit, Michigan 48201 , USA Primary cultures of rat renal proximal tubular (PT) and distal tubular (DT) cells from control and uninephrectomized (NPX) Sprague-Dawley rats were established to study whether the altered toxicological responses identified in freshly isolated cells are maintained in culture. Previous work showed that primary cultures of PT cells from hypertrophied rat kidneys maintained their differentiated properties, as evidenced by their high respiratory rate, active transport function, transport and metabolism of glutathione, and their hypertrophic phenotype. In the present study, primary cultures of PT cells from NPX rat kidneys, but to a much lesser extent DT cells, were more susceptible to cellular injury induced by either mercuric chloride, KCN, or tert-butyl hydroperoxide (tBH), than corresponding cells from normal rat kidneys. Direct comparisons of cytotoxicity and lipid peroxidation induced by tBH in freshly isolated renal cells showed that the primary cultures of cells from NPX rat kidneys retained their altered susceptibility relative to cells from control rats. These results show that primary cultures of PT cells from NPX rats are more sensitive to cellular injury induced by three mechanistically distinct toxicants, demonstrating their usefulness in the study of the molecular and biochemical basis for the altered phenotype of compensatory renal growth. This is the first report validating the use of a mammalian renal cell culture model to study the toxicological effects of compensatory renal cellular hypertrophy. Key Words: compensatory renal growth; proximal tubular cells; primary cell culture; susceptibility; mercuric chloride; oxidative stress. Reductions of functional renal mass can occur in humans as a consequence of renal disease, surgery, or aging. These reductions in renal mass induce compensatory changes in the remaining viable nephrons (especially along the proximal tubule) and are characterized primarily by profound morphological and functional changes, including increases in cell size, plasma membrane surface area, single-nephron glomerular filtration rate, rates of sodium transport, overall protein content, mitochondrial respiration, and glutathione (GSH) transport and metabolism (Harris et al., 1988; Lash and Zalups, 1994; Lash et al., 2001a,b; Meyer et al., 1996; Nath et al., 1990; Zalups and Lash, 1990) . Uninephrectomized (NPX) rats have been commonly used as a model to study compensatory renal growth. The acute hemodynamic, functional, and biochemical effects associated with reduced renal mass and compensatory growth are nearly complete in rats within 7–10 days postnephrectomy and are maintained for at least 30 days thereafter (Meyer et al., 1996; Shirley and Walter, 1991; Zalups et al., 1987) . Although varied changes occur throughout the nephron, the most prominent changes occur in the proximal tubular (PT) region (Meyer et al., 1996; Shirley and Walter, 1991) . Compensatory renal cellular hypertrophy also has toxicological implications. Several studies have shown that NPX rats exhibit altered susceptibility (increased in most cases) to renal cellular dysfunction and injury induced by a variety of nephrotoxicants, including inorganic mercury (Hg2þ) (Zalups, 1997, 2000; Zalups and Diamond, 1987; Zalups and Lash, 1994) , analgesics (Henry et al., 1983; Molland, 1976) , and cadmium-metallothionein (Zalups et al., 1992) . Despite the wealth of literature showing associations between toxicity and various cellular processes that are altered by compensatory renal growth, detailed mechanisms explaining altered susceptibility to nephrotoxicants are lacking. To study the biochemical and toxicological impact of uninephrectomy and compensatory renal growth in the rat kidney, we previously used suspensions of freshly isolated renal PT cells from NPX rats as an in vitro model system (Lash and Zalups, 1992, 1994) . Suspensions of isolated distal tubular (DT) cells were also used as an alternative renal cell population that is not influenced by compensatory renal growth to the same degree as PT cells. Our previous findings show that PT cells from NPX rats retain their hypertrophied phenotype upon isolation and exhibit (relative to PT cells from control rats) increased cell size, GSH content, rates of GSH transport and metabolism, mitochondrial oxidative phosphorylation, and sensitivity to cytotoxicity induced by Hg2þ (Lash and Zalups, 1992, 1994) . (...truncated)


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Lash, Lawrence H., Putt, David A., Zalups, Rudolfs K.. Influence of Compensatory Renal Growth on Susceptibility of Primary Cultures of Renal Cells to Chemically Induced Injury, Toxicological Sciences, 2006, pp. 417-427, Volume 94, Issue 2, DOI: 10.1093/toxsci/kfl105